Internal heat exchanger

ABSTRACT

An internal heat exchanger includes an inner tube for a flow of a first fluid; an outer tube that is coaxial with the inner tube; a passageway between the inner tube and the outer tube for a flow of a second fluid; and, a flow enhancer inside the inner tube and configured to divert the flow of fluid in the inner tube along a wall of the inner tube.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of international patentapplication PCT/US2013/054449, filed Aug. 11, 2013 which designates theUnited States and claims priority from United States ProvisionalApplication No. 61/681,668 filed Aug. 10, 2012. The present continuationapplication claims priority to each of the above applications andincorporates herein the entire contents thereof by reference.

FIELD OF THE INVENTION

The present disclosure relates to an internal heat exchanger, and moreparticularly to a double tube internal heat exchanger for a vehicle.

BACKGROUND OF THE INVENTION

Internal heat exchanger assemblies are now being used on vehicle airconditioning systems to improve performance and system efficiency.Efficiency and performance gains are achieved by the use of a coaxialheat exchanger where the liquid refrigerant is flowed around the outsideof the suction tube.

Heat is transferred from the liquid to the suction line which increasessub-cooling in the liquid line.

SUMMARY OF THE INVENTION

The present invention includes an internal heat exchanger for a vehiclewith improved suction line flow. The internal heat exchanger has aninner tube and an outer tube. The inner tube and outer tube are coaxialwith one another. A flow enhancer is disposed within the inner tube todivert flow of fluid towards an outer wall of the inner tube. The flowdiversion aids in the transfer of heat to the outer wall therebyimproving the efficiency of the heat exchanger.

The flow enhancer may be an elongate shape and may be formed, forexample, from an extrusion process. The flow enhancer can be shaped soas to divert flow towards the outer wall of the inner tube whileblocking the flow of fluid from the middle of the tube. For example, theflow enhancer may be an elongate member having a generally cylindricalcentral portion and a plurality of radially extending longitudinal fins.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the drawingswherein:

FIG. 1 is a spring internal heat exchanger;

FIG. 2A shows a view of a multi-channel internal heat exchanger;

FIG. 2B shows a section along line 2B-2B of FIG. 2A;

FIG. 2C shows a view of a multi-channel internal heat exchanger;

FIG. 3A is an embodiment of a flow enhancer in accordance with aspectsof the invention;

FIG. 3B is an embodiment of a suction tube;

FIG. 3C is an embodiment of an assembly of the flow enhancer and suctiontube of FIGS. 3A and 3B;

FIG. 4A is an embodiment of an assembly of a flow enhancer, a suctiontube and a liquid tube of a channel internal heat exchanger;

FIG. 4B is an embodiment of an assembly of a flow enhancer, a suctiontube and a liquid tube of a spring internal heat exchanger;

FIG. 5A is an embodiment of a spring internal heat exchanger having aflow enhancer; and,

FIG. 5B is an embodiment of a channel internal heat exchanger having aflow enhancer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 is a spring internal heat exchanger 10. FIGS. 2A to 2C showvarious views of a channel heat exchanger 20. Both heat exchangers (10,20) include an inner tube 30 and an outer tube 32 that are coaxial withone another. The inner tube 30 is the return line (also referred to as a“suction line”) of a refrigeration system. The inner tube 30 and outertube 32 are separated by a passageway. In the spring heat exchanger 20,the inner tube 30 and outer tube 32 are separated by a spring 34 forminga helical passageway between the tubes. In the channel heat exchanger30, the inner tube 30 and outer tube 32 are separated by a plurality ofribs 36 that form one or more channel-shaped passageways 38.

Referring now to FIGS. 3A to 3C, the heat exchangers (10, 20) are shownwith a flow enhancer 50. The flow enhancer 50 may be an elongate member.The elongate member may be formed by an extrusion process. As shown bestin FIG. 3A, the flow enhancer 50 has a central portion 52 that extendsaxially and a plurality of radial members 52 (for example, ribs) thatextend along the axial length of the flow enhancer. In one embodiment,at least one radial member can be a continuous fin that extends alongthe full axial length of the flow enhancer. Additionally oralternatively, the flow enhancer may include a plurality of fins thatextend along a portion of an axial length of the flow enhancer (forexample, less than the full axial length of the flow enhancer).

The central portion 52 may have a substantially circular cross-section.The flow enhancer 50 is assembled with the inner tube 30 such that theflow enhancer 50 and inner tube 30 are coaxial with one another. Theouter portions 54 of the radial members 52 may be in contact with theinner tube 30, as shown in FIG. 3C.

The flow enhancer 50, and in particular, the central portion 52, blocksflow in the center of the inner tube 30 (suction tube) and diverts orforces the flow against a wall 51 of the tube 30. The central portion 52and radial members 54 can be configured to minimize pressure drop acrossthe internal heat exchanger. The flow enhancer may be formed from acomposite material that may be bendable with the inner and outer tubes.In one embodiment, the flow enhancer is constructed from a compositematerial that does not substantially affect heat transfer.

Referring still to FIGS. 3A to 3C, the material can, for example, alsobe composite plastic, nylon or any metal such as aluminum, copper or acombination of metal and plastic. The rib design may or may not becontinuous.

FIG. 4A is an embodiment of an assembly of a flow enhancer, a suctiontube and a liquid tube of a channel internal heat exchanger wherein therib edge is in contact with the suction tube inner diameter. FIG. 4B isan embodiment of an assembly of a flow enhancer, a suction tube and aliquid tube of a spring internal heat exchanger wherein the rib edge isin contact with the suction tube inner diameter.

FIG. 5A is an embodiment of a spring internal heat exchanger having aflow enhancer and FIG. 5B is an embodiment of a channel internal heatexchanger having a flow enhancer.

It is understood that the foregoing description is that of the preferredembodiments of the invention and that various changes and modificationsmay be made thereto without departing from the spirit and scope of theinvention as defined in the appended claims.

What is claimed is:
 1. An internal heat exchanger comprising: an innertube for a first flow of a first fluid; an outer tube; said inner tubeand said outer tube being coaxial to each other; said inner tube andsaid outer tube conjointly defining a passageway therebetween for asecond flow of a second fluid; said inner tube having an inner tubewall; and, a flow enhancer arranged inside said inner tube andconfigured to divert said first flow of said first fluid along saidinner tube wall.
 2. The internal heat exchanger of claim 1, wherein saidflow enhancer is an elongate member.
 3. The internal heat exchanger ofclaim 1, wherein said flow enhancer includes a central portion and aplurality of radial members extending from said central portion.
 4. Theinternal heat exchanger of claim 3, wherein said central portion has acylindrical shape.
 5. The internal heat exchanger of claim 3, whereinsaid radial members each have an outer portion in contact with saidinner tube.
 6. The internal heat exchanger of claim 1 further comprisinga spring arranged between said inner tube and said outer tube.
 7. Theinternal heat exchanger of claim 1 further comprising a plurality oflongitudinal channels between said inner tube and said outer tube. 8.The internal heat exchanger of claim 1, wherein said flow enhancer andsaid inner tube wall conjointly define a plurality of channelstherebetween.
 9. A flow enhancer for an internal heat exchangercomprising: an axially extending central body; and, a plurality ofradial members extending from said central body.
 10. The flow enhancerof claim 9, wherein: said central body has an axial length; and, atleast one of said radial members is a continuous fin extending over thefull extent of said axial length.
 11. The flow enhancer of claim 9,wherein: said central body has an axial length; and, said radial memberscomprise a plurality of fins that extend along a portion of said axiallength.